The present invention relates generally to the field of magnetic data storage and retrieval systems. More particularly, the present invention relates to a magnetic recording head with a point writer pole.
A magnetic head for recording generally consists of two portions, a writer portion for storing magnetically-encoded information on a magnetic media (disc) and a reader portion for retrieving that magnetically-encoded information from the media. The reader portion of the magnetic head consists of a bottom shield, a top shield, and a sensor, often composed of a magnetoresistive (MR) material, positioned between the bottom and top shields. Magnetic flux from the surface of the disc (media) causes rotation of the magnetization vector of a sensing layer of the MR sensor, which in turn causes a change in electrical resistivity of the MR sensor. The change in resistivity of the MR sensor can be detected by passing a current through the MR sensor and measuring a voltage across the MR sensor. External circuitry then converts the voltage information into an appropriate format and manipulates that information as necessary to recover the data that was encoded on the disc.
The writer portion of the magnetic head typically consists of a main pole and a return pole which are magnetically separated from each other at an air bearing surface (ABS) of the writer by a nonmagnetic gap layer, and which are magnetically connected to each other at a region distal from the ABS by a back gap closure. Positioned at least partially between the main and return poles are one or more layers of conductive coils encapsulated by insulating layers. The ABS is the surface of the magnetic head immediately adjacent to the medium. The writer portion and the reader portion are often arranged in a merged configuration in which a shared pole serves as both the top or bottom shield of the reader portion and the return pole of the writer portion.
To write data to the magnetic medium, an electrical current is caused to flow through the conductive coil, thereby inducing a magnetic field across the write gap between the main and return poles. By reversing the polarity of the current through the coil, the polarity of the data written to the magnetic media is also reversed. Data on double layer perpendicular media are recorded by a trailing edge of the main pole. Accordingly, it is the main pole that defines the track width of the written data. More specifically, the track width is defined by the width of the main pole at the ABS.
In magnetic recording, it is desirable to improve the areal density of information that can be recorded and reliably read. This desire has led to a trend toward shorter bit length along a magnetic recording track and a shrinking track width. Narrow track widths are achieved by use of narrow pole tips at an air bearing surface (ABS) of the head. However, the pole width must be large in the body region of the head where the coil passes between the poles. The larger pole width is necessary to gain adequate magnetic flux through the poles by the coil write current. Hence, it is common to taper the pole from the larger width in the body region to a narrower width in the pole tip region at the ABS. However, forming a write pole having the desired narrow width at the pole tip region has posed many challenges.
Forming the write pole tip has been done by patterning the write pole shape using a photoresist process. However, as the dimensions desired for the write pole tip decrease, the limit has been reached for using a photoresist method. Specifically, the wave length of the light used to develop the photoresist is larger than the pattern to be exposed, making it impossible to develop a photoresist pattern having the desired small dimensions. It is possible to use an x-ray or electron beam machine to address this problem, but such machines are extremely expensive.
In addition, due to the complexity of the magnetic recording head, forming the writer and reader portions on the magnetic head involves several manufacturing processes. Typically, many magnetic recording heads are formed on a wafer structure using a variety of deposition, masking, milling, etching, and/or other similar processing steps. Once the magnetic recording heads are formed, the wafer may be further processed and is sliced into bars and ultimately is separated into individual sliders. This entire process can take a significant amount of time, up to six weeks with the manufacturing process operating twenty four hours a day, seven days a week. Each additional process step required to form the magnetic recording head increases the cost of manufacturing, increases the time needed for forming the magnetic head, and may increase the likelihood of manufacturing errors which affect the final performance of the magnetic head.
Thus, there is a need in the art for a magnetic recording head having a narrow write pole width, as well as a cost effective and time efficient method of manufacturing such a narrow write pole.